In endeavors (such as plumbing) that deal with pipes, tubes or other cylindrical objects, it is common to use threaded inserts for end pieces, and the like. When threaded connections are used, the threads are often designed so that the taper of the threads forces internal and external threads to seal against each other to affect a tightly sealed joint capable of holding water, gas, or the like. In order to assure a tight seal, the installer will apply as much force as possible to affect proper air tight or water tight integrity in the system. In many applications, a glue, sealing compound, or putty is applied to the threads or near the threads at the time of installation. This is particularly prevalent for systems containing gas or volatile substances. While this is considered an excellent approach at the time of installation, the use of sealing compounds or the like to effect tight connections also introduces subsequent problems.
Pipe and tube systems are not invulnerable, and thus, deterioration can be expected to take place from a variety of causes. This means that maintenance must be performed, very often with the removal for cleaning or replacement, of various parts of the system, including connected pipes or tubes. Even if the system is being “scrapped”, parts of the system may still be useful, and thus salvage is desirable with as little damage as possible. Accordingly, non-destructive disassembly of the system is very desirable, where possible. Unfortunately, non-destructive disassembly can be impossible when pipes or tubes rust or corrode, rendering threaded connections (especially those treated with joining compound) as virtual unitary masses.
Conventional tools, in particular various types of wrenches, used for installation of pipes, tubes and the like are seldom adequate for breaking the seal in threaded joints created by solidified joint compound or/and corrosion. Exterior wrenches (such as pipe wrenches and the like) are often difficult to use in close quarters when applying the forces necessary to break a sealed threaded connection. Further, even when a sufficient force can be applied, the body of the tube or pipe is more likely to break than the sealed, reinforced sections at the threaded connection.
When threaded connections are sealed and cannot be broken, a number of solutions are known in the plumbing or pipe fitting art. One traditional solution is simply to cut away the sealed joints, thereby sacrificing that portion of the system with regard to recycling, and perhaps damaging other parts. The cost for this waste is generally fairly slight, at least in terms of material. However, the cost in the time expended by skilled workers in cutting away the sealed joints is considerable. As a result, the cost for dealing with the disassembly, maintenance or repair of a pipe or tube system can be as great as the original installation of this system. This can be disastrous in terms of maintaining low cost levels for repair, salvage, and the like.
Of particular difficulty are drain inserts for tubs, sinks or other structures which interface with the end of a pipe, and form a seal between the sink and the end of the pipe. When a threaded joint between a drain insert and the pipe terminating at the drain insert becomes locked (by means of corrosion and/or compound) so that it cannot be rotated, special problems occur with regard to maintenance, repair or replacement. The standard method of cutting a pipe using a hacksaw does very little good with regard to removing the drain insert, even if cutting the pipe is a necessary preliminary step for removing the drain insert. Cutting out a drain insert is difficult, time consuming, and very often results in a damaged sink or other vessel.
One example of a cutting tool for removing drain inserts or assemblies is found in U.S. Pat. No. 5,946,990 to Bonacci, (incorporated herein by reference). Those who have used such arrangements attest to the difficulty and costs of removing drain inserts by such techniques. Even a skilled practitioner is liable to damage a salvageable sink or other vessel, and entirely destroy the threaded end of the feed pipe, necessitating substantial replacement, as well as labor costs.
Another arrangement is the use of internal wrenches. A wide variety of internal wrench arrangements have been used. These include: U.S. Pat. No. 6,343,411 to Sigman; U.S. Pat. No. 7,024,972 to Werner et al.; U.S. Pat. No. 4,499,799 to Bordages; U.S. Pat. No. 6,874,393 to Kile; U.S. Pat. No. 5,257,559 to Cannetti; U.S. Pat. No. 6,282,999 to Hite et al; U.S. Pat. No. 2,956,461 to Anderson; and, U.S. Pat. No. 6,675,679 to Dugan. All of these devices and systems are incorporated herein by reference.
Of all of these designs, argueably the most effective is found in U.S. Pat. No. 6,675,679, to Dugan. This design employs a gripping device, having a split shell, which is adjusted for gripping the interior of a pipe or tube through the use of a cam like structure. While the subject device disclosed in the Dugan patent has proven largely superior to other systems for removing drain inserts, there are still difficulties in the actual operation of the Dugan arrangement. Firstly, the gripping adjustment of the Dugan arrangement is difficult to maintain when attaching the external wrench necessary to separate the drain insert from the feed pipe. Even skilled practitioners have difficulty operating the Dugan arrangement in an expeditious and satisfactory matter. Generally, more than two hands are needed to hold the Dugan device in a gripping position and then place the external wrench on the device for operation.
Another problem with the Dugan arrangement, as well as the other conventional arrangements cited and incorporated by reference, results from pipe deterioration, which is frequently the situation when repair, maintenance or recovery are being conducted. In particular, rusted or otherwise deteriorated pipes tend to break easily, especially near the L-shaped section at the drain insert. When this happens, the internal wrench of Dugan (or one of the other arrangements from the cited art) will operate to spin the broken end (L-shaped section) of the pipe, without separating it from the drain insert. When this happens, conventional cutting of the drain insert is the only course to take. When this happens, the whole purpose of the relatively expensive and complex internal wrench of Dugan has been undermined.
Accordingly, the art of internal pipe wrenches, especially those used to remove drain inserts, admits to a substantial improvement. For example, such an improvement would facilitate the continued use of the internal wrench without cutting, even with a broken pipe. Further, such improvements would include the facilitation of easy adjustable gripping and operation.